Controlling valve operation using pressure

ABSTRACT

A valve body has a piston that slides within the body through four successive positions. The piston has a head, and an upper and lower skirt, with a port in the upper skirt. In the first position, a bias force urges the piston to the first of four positions, in which the piston port is closed. In a second position, the piston port aligns with a low pressure port in the valve body, when a low pressure supply of water is connected. In a third position, greater pressure again closes the piston port. In a fourth position, at a still greater pressure, the piston port aligns with a high pressure port in the valve body. The bias force or a location of the piston port can be varied for valves along a supply line, whereby varying supply pressure opens different valves, thereby enabling addressing of valves according to supply pressure.

FIELD OF THE DISCLOSURE

The disclosure relates to a system and method for selectively addressingsets of irrigation valves, and in particular using valves which open atdifferent pressures due to mechanical differences among the valves.

BACKGROUND OF THE DISCLOSURE

European Patent Application EP0537849A1 discloses automatic pulsatingdeliver of an irrigation liquid by using pressure-sensitive secondaryvalves which open or close to enable irrigation liquid to emerge.

U.S. Pat. No. 391,774 discloses emitters of different flow potential forsupplying the same given amount of water at various line pressures.Specific line pressure at each hole in the feeder tube is measured andan emitter adapted to deliver the desired amount of water is selectedand installed at the location.

U.S. Pat. No. 6,786,425 discloses an actively operable check valve toselectively exert first and second pressures on the check valve. Thevalve permits the passage of spray fluid at one of the first and secondpressures.

U.S. Pat. No. 8,348,182 discloses an irrigation pipe with integratedemitters having different discharge-pressure thresholds.

U.S. Patent Publication 2005/0279856 discloses a pipe and emitterassembly having a sealing adapter, an emitter tube, and a pressurecompensating flow emitter. A controller adjusts irrigation parametersbased on data.

U.S. Patent Publication 2014/0374502 discloses a flow regulating dripemitter with labyrinth passageways with different resistance to waterflow, wherein movement of a cover selects a passageway.

PCT Publication WO 2010/061375 A1 discloses a drip irrigating systemwith a pulsating device that converts a low continuous liquid flow rateto a high intermittent and pulsating flow rate, connected to a manifoldof pressure-compensated drippers.

SUMMARY OF THE DISCLOSURE

In an embodiment of the disclosure, a valve, comprises a valve bodyincluding an interior surface; a fluid inlet communicating fluid into aninterior of the valve body; a piston slideable successively throughfirst, second, third, and fourth positions within the valve body andincluding: a head, a skirt forming an upper skirt portion connected toand extending from the head in a direction of the fluid inlet, the upperskirt portion forming a seal against the interior surface of the valvebody; a piston port formed in the upper skirt portion; a low pressureport formed through the interior surface of the valve body, the lowpressure port sealed against the interior of the valve body when thepiston is in the first and third positions, the low pressure port influid communication with the piston port when the piston is in thesecond position; a high pressure port formed through the interiorsurface of the valve body, the high pressure port in fluid communicationwith the piston port when the piston is in the fourth position; and abiasing element positioned within the valve body to urge the piston headin a direction of the first position, the piston moveable against abiasing force of the biasing element to slide successively from thefirst to the fourth position as the pressure at the fluid inlet isincreased.

In variations thereof, the valve further includes a lower skirt portionconnected to and extending from the head in a direction away from thefluid inlet, the lower skirt portion forming a seal against the interiorsurface of the valve body; the lower skirt portion forming a sealagainst the low pressure port and the high pressure port when the pistonis in the first position; the lower skirt portion forming a seal againstthe high pressure port when the piston is in the second position; and/orthe lower skirt portion forming a seal against the high pressure portwhen the piston is in the second position and the third position, theupper skirt portion forming a seal against the low pressure port whenthe piston is in the third position.

In further variations thereof, the biasing element is a spring; thevalve further includes at least one tab connected to the valve body andslideable within a slot in the piston skirt to prevent rotation of theskirt; and/or the piston has the form of a cylinder; and/or the valvefurther includes a lower skirt portion connected to and extending fromthe head in a direction away from the fluid inlet, the piston formingthe shape of a cylinder having two open ends, and an interior closed bythe piston head.

In another variation thereof, the valve further includes a fluidretaining chamber disposed at an outlet of at least one of the low andhigh pressure ports; and a membrane dividing the chamber, the membranedisplaceable by fluid passing under pressure into the chamber from theat least one of the low and high pressure ports, the membrane movable toa non-displaced configuration to gradually release fluid passed into thechamber when fluid is not passing into the chamber.

In another embodiment of the disclosure, a method of irrigating plantscomprises positioning along a supply line of water, a plurality ofvalves, each valve including: a valve body including an interiorsurface; a fluid inlet communicating fluid into an interior of the valvebody; a piston slideable successively through first, second, third, andfourth positions within the valve body and including: a head, a skirtforming an upper skirt portion connected to and extending from the headin a direction of the fluid inlet, the upper skirt portion forming aseal against the interior surface of the valve body; a piston portformed in the upper skirt portion; a low pressure port formed throughthe interior surface of the valve body, the low pressure port sealedagainst the interior of the valve body when the piston is in the firstand third positions, the low pressure port in fluid communication withthe piston port when the piston is in the second position; a highpressure port formed through the interior surface of the valve body, thehigh pressure port in fluid communication with the piston port when thepiston is in the fourth position; a biasing element positioned withinthe valve body to urge the piston head in a direction of the firstposition, the piston moveable against a biasing force of the biasingelement to slide successively from the first to the fourth position asthe pressure at the fluid inlet is increased configuring first andsecond sets of valves differently, wherein configuring differentlyincludes providing valves in the first set relative to the second setwith at least one of a different biasing element and a differentposition of the low pressure port, wherein the low pressure port ofvalves of the first set open at a first pressure, and the low pressureport of valves of the second set open at a second pressure greater thanthe first pressure, and the low pressure port of the first set areclosed at the second pressure; supplying water to the supply line at thefirst pressure wherein valves of the first set flow water, and valves ofthe second set do not flow water; and supplying water to the supply lineat the second pressure, wherein valves of the second set flow water, andvalves of the first set do not flow water.

In variations thereof, configuring includes opening the valve body andreplacing at least one of the piston and the biasing element, andclosing the valve body; the biasing element is a gas or liquid underpressure admitted to a side of the piston head opposite to a side of thepiston head in fluid communication with the fluid inlet; the supply lineis at least 600 feet; the supply line is a drip irrigation supply line;and/or the piston further includes a lower skirt portion connected toand extending from the head in a direction away from the fluid inlet,the lower skirt portion forming a seal against the interior surface ofthe valve body, and wherein supplying water at the first pressureincludes blocking the high pressure port with the lower skirt portion.

In another variation thereof, the piston further includes a lower skirtportion connected to and extending from the head in a direction awayfrom the fluid inlet, the lower skirt portion forming a seal against theinterior surface of the valve body, and wherein supplying water at anintermediate pressure between the first pressure and the second pressureincludes blocking the low pressure port with the upper skirt portion,and blocking the high pressure port with the lower skirt portion.

In another variations thereof, the method further includes supplyingwater at a third pressure higher than the first pressure and the secondpressure, wherein the high pressure port of all of the first and secondsets of valves are open.

In a further variation thereof, the valve further includes a fluidretaining chamber disposed at an outlet of at least one of the low andhigh pressure ports; a membrane dividing the chamber, the membranedisplaceable by fluid passing through the piston port and out of thevalve body and into the chamber, the membrane movable to a non-displacedconfiguration to gradually release fluid passed into the chamber whenfluid is not passing into the chamber; wherein when supplying water tothe supply line at the first pressure, water is passed into the chamberfrom the low pressure port; and wherein when supplying water to thesupply line at the second pressure, water does not pass into thechamber, and water passed into the chamber while applying the firstpressure is gradually released.

In a further embodiment of the disclosure, a method of irrigating plantscomprises positioning along a supply line of water, a plurality ofvalves, each valve including: a valve body including an interiorsurface; a fluid inlet communicating fluid into an interior of the valvebody; a piston slideable successively through first, second, third, andfourth positions within the valve body and including: a head, a skirtforming an upper skirt portion connected to and extending from the headin a direction of the fluid inlet, the upper skirt portion forming aseal against the interior surface of the valve body; a piston portformed in the upper skirt portion; a low pressure port formed throughthe interior surface of the valve body, the low pressure port sealedagainst the interior of the valve body when the piston is in the firstand third positions, the low pressure port in fluid communication withthe piston port when the piston is in the second position; a highpressure port formed through the interior surface of the valve body, thehigh pressure port in fluid communication with the piston port when thepiston is in the fourth position; a biasing element positioned withinthe valve body to urge the piston head in a direction of the firstposition, the piston moveable against a biasing force of the biasingelement to slide successively from the first to the fourth position asthe pressure at the fluid inlet is increased wherein the plurality ofvalves include first and second sets of valves, and wherein valves inthe first set relative to the second set have at least one of adifferent biasing element and a different position of the low pressureport, wherein the low pressure port of valves of the first set open at afirst pressure, and the low pressure port of valves of the second setopen at a second pressure greater than the first pressure, and the lowpressure port of the first set are closed at the second pressure;addressing the first or second set of valves by supplying water to thesupply line at the first pressure wherein valves of the first set flowwater, and valves of the second set do not flow water, and supplyingwater to the supply line at the second pressure, wherein valves of thesecond set flow water, and valves of the first set do not flow water;and supplying water at a third pressure higher than the first pressureand the second pressure, wherein the high pressure port of all of thefirst and second sets of valves are open and flow water.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 depicts a valve of the disclosure, drawn enlarged with respect tothe valves of FIGS. 3-8, for clarity, the valve in a closed position inwhich fluid does not flow through the valve;

FIG. 2 is a perspective view of an embodiment of the piston of FIG. 1;

FIG. 3 depicts the valve of FIG. 1, in which a low pressure port isopen;

FIG. 4 depicts the valve of FIG. 1, in an intermediate, closed position;

FIG. 5 depicts the valve of FIG. 1, in which a high pressure port isopen;

FIG. 6 depicts the valve of FIG. 1, in which a position of the lowpressure port is changed, and a stiffness of a biasing element ischanged;

FIG. 7 depicts the valve of FIG. 3, further including a reservoir andmembrane which have been charged with a supply of fluid;

FIG. 8 depicts the valve of FIG. 7, in which the valve is in anintermediate, closed position, and in which the charge of fluid isgradually released by pressure imparted by the membrane; and

FIG. 9 depicts graphs of pressure and flow for two valves of thedisclosure which have been configured to open a low pressure port atrelatively different input pressures, and which have a high pressureport which opens at the same pressure.

DETAILED DESCRIPTION OF THE DISCLOSURE

As required, detailed embodiments are disclosed herein; however, it isto be understood that the disclosed embodiments are merely examples andthat the systems and methods described below can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present subject matter in virtually anyappropriately detailed structure and function. Further, the terms andphrases used herein are not intended to be limiting, but rather, toprovide an understandable description of the concepts.

The terms “a” or “an”, as used herein, are defined as one or more thanone. The term plurality, as used herein, is defined as two or more thantwo. The term another, as used herein, is defined as at least a secondor more. The terms “including” and “having,” as used herein, are definedas comprising (i.e., open language). The term “coupled,” as used herein,is defined as “connected,” although not necessarily directly, and notnecessarily mechanically.

Drip line irrigation methods are used widely in agriculture to reduceoverall water consumption and to more accurately supply water insynchrony with the plants consumption requirements. As sensor methodsincluding satellites have improved, it has become possible to determinewith fine granularity the local needs of a field, and in some cases ofan individual plant. This makes it desirable to control sections or evenindividual drip valves. In a long drip line, it is possible toelectronically control each drip valve, but this increases the cost andcomplexity of an irrigation system, and reduces reliability.

In accordance with the disclosure, a method and system are providedwhich provide fine granularity control using a simple mechanicalstructure, avoiding a requirement of electronic valve controls or othercomplex approaches. A system of the disclosure enables “addressing” anyvalve, or group of valves, simply due to a pressure level within asingle supply line. As such, it is possible to address and open valveson a drip line, or higher pressure line, based on line pressureregulated at the source end of the irrigation line, and for any lengthof line. Each valve of the disclosure has at least one specific pressureat which the valve will open. At other pressures the valve will remainclosed.

In a drip irrigation line, the pressure along the line will vary, withhigher pressure at the end of the water supply point and the start ofthe drip irrigation line, with water pressure dropping toward the end ofthe line. The valves operations is enabled around the equilibriumpressure of the line by modulating the pressure at the location of thevalve. Increase or decrease of the pressure will open/close the valveand enable irrigation.

With reference to FIGS. 1-5, a valve 100 includes an inner piston 200and an outer body 300. Piston 200 is shown in perspective in FIG. 2, andincludes an upper piston skirt 202 which forms a watertight seal, alongat least a portion of its length, against an inner surface 302 ofcylinder 304 of body 300, and which forms an inlet chamber 202A in fluidcommunication with an inlet 306. In this manner, fluid which enters froma supply line (not shown) through inlet 306, can only pass through valve100 by passing through piston port 204, and can only do so when port 204aligns with a cylinder low pressure port 308 or a cylinder high pressureport 310. Piston head 210 is driven away from inlet 306 by pressurizedfluid which enters inlet 306.

An underside 212 of piston head 210 is contacted by a biasing element400 which urges piston 200 in the direction of arrow “A” and into aposition in which port 204 is closed, and is sealed against innersurface 302, and in which no fluid flows through valve 100. Biasingelement 400 can have the form of a spring, as diagrammaticallyillustrated in the figures. It should be understood that biasing element400 can have any known form, including a conical spring as shown, or anyother type of spiral spring, including a barrel or hourglass typespring. Alternatively, biasing element 400 can be a pressurized bladder,or a leaf spring, and can be made of any resilient material. Biasingelement can be a constant or progressive rate spring, whereby therelationship to an amount of input pressure required for opening of port308 and port 310 can be linear or non-linear.

A cylinder equalizing port 312 can be provided to enable pressure toequalize on the underside of piston head 210. Piston skirt 202 cansimilarly be provided with pressure equalizing port 214 or other openingwhich communicates between pressure relief opening 312 and an interiorvolume defined by piston underside 210 and skirt 202.

In an alternative embodiment, equalizing port 312 can be used as apressurizing port, and can be supplied with a fluid, such as air orwater, at a predetermined amount of pressure, to thereby set a desiredamount of biasing force applied to piston underside 212, thereby settinga particular pressure at which ports 204 and 308, or ports 204 and 310,align and open.

When either port 308 or port 310 is in fluid communication with port204, fluid can flow from a supply line through inlet 306 to a manifold314 and then to outlet 316 and then to plants which are to be watered,or to supply fluid for any other purpose, including non-agriculturalapplications.

An alignment tab 320 can be provided, extending from inner surface 302of cylinder 304, tab 320 passing through an alignment slot 220 in alower piston skirt 222 of piston 200 during travel of piston 200, tothereby prevent radial rotation of piston 200 and a consequentmisalignment of port 204 with port 308 or 310, and port 214 with port312. Tab 320 can further cooperate with an extent of slot 220, to limittravel of piston 200. Additionally, lower piston skirt 222 seals againstinner surface 302, sealing ports 308 and 310 when they are not alignedwith port 204, and prevents backflow of fluid from outlet 316 into valvebody 300 during operation of valve 100.

With reference to FIG. 3, as shown by arrow “B”, fluid has been admittedinto inlet 306 at a first pressure which drives piston 200 downwardswhen viewed in the figure, whereby ports 204 and 308 align, and fluidcan pass through valve 100.

In FIG. 4, the pressure of fluid at inlet 306 has been increasedrelative to the pressure applied with respect to FIG. 3, and piston 200has been displaced further away from inlet 306, against a biasing forceapplied by biasing element 400, to once again seal port 204 against aninner surface 302 of cylinder 304, whereby no fluid can pass throughvalve 100. In this embodiment, the pressure at inlet 306 is intermediatewith respect to a pressure operative to open port 308 and 310,respectively.

In FIG. 5, as the pressure of fluid at inlet 306 is further increased,piston 200 is further displaced away from inlet 306, and port 204 alignswith high pressure port 310, and fluid can once again flow through valve100 following the path defined by arrow “C”. A progressively greaterpressure at inlet 306 is required to move piston from a positionaligning port 204 with port 308, to a position sealing port 204, andthen to a position aligning port 204 with port 310, because biasingelement 400 imparts a progressively greater resistance to movement ofpiston 200. In this manner, port 308 is defined as a low pressure portrelative to port 310.

The amount of pressure required to enable fluid to flow through port 204is dependent on any one or all of the following parameters: a diameterof piston 200, a location of port 204 along skirt 202, a location ofport 308, an extent of biasing pressure by biasing element 400, aprogressive profile of biasing element 400, an amount of fluid pressureat inlet 306. Other elements which impact fluid flow includebackpressure at outlet 316, and stiction or other resistance to movementof the components of valve 100.

Accordingly, the aforedescribed parameters can be changed as part of thedesign of valve 100, or some of them can be changed in the field, toachieve desired operating parameters of valve 100. For example, as shownin FIG. 6, an end portion 322 of body 300 can be removed or opened, forexample using a threaded connection 324, whereby biasing element 400 canbe substituted. Likewise, piston 200 can be replaced with a piston 200and piston skirt 202 of different configuration as described herein,released and reconnected for example be removing and replacing tab 320.As further illustrated in FIG. 6, biasing element 400 can be changed, alocation of port 204 can be raised or lowered, and configuration ofmanifold 314 and a location of ports 308 or 310 can be changed. In theexample of FIG. 6, port 204 has been raised towards inlet 306, totherefore require greater pressure in order to be opened. Valve openingscan also be enlarged or reduced in size, to change flow rate. It shouldbe understood, however, that any one change, or combination of changescan be made, to achieve a desired change in operating characteristics,and particularly, pressures at which port 308 or 310 will be opened. Inthis manner, any number of valves 100 can be deployed along a singlesupply line, and each differently configured valve 100 or group ofdifferently configured valves 100 will open port 204 at a differentpredetermined low pressure force

For example, valves 100 can be arrayed along a supply line so that asfluid pressure is progressively increased, valves will sequentially openand close along the line, watering crops along the line sequentially.This can be advantageous for a variety of reasons, including reducingoverall water usage, maintaining pressure in a long line, wateringdifferent crops at different places along the line for different periodsof time, reducing waste, and reducing water runoff.

While pressure can be increased to sequentially water successive crops,it is also possible to selectively set the supply line pressure toaddress a particular operating pressure of valve 208 of differentlyconfigured valves, regardless of where they have been located along oneor more supply lines. In this manner, particular valves 100 areactivated at a given pressure, and therefore particular crops which aresupplied by those valves. In this manner, crops which require water atdifferent parts of the day, or for different periods of time, can beselectively addressed according to their requirements by changing thesupply pressure of a supply line.

By providing a high pressure port 310 as shown and described, it ispossible to increase pressure in a supply line to a point where allvalves open. This can be useful, for example, to ensure that all cropsreceive water during peak dry periods, or to provide protection againstdamage to an irrigation system due to excessive supply line pressure.

In an embodiment, different valves 100 can be configured to open port310 at different pressures, by configuring a location of port 310, orchanging a biasing force of biasing element 400, thereby providingadditional options for configuring valve 100. Despite differingoperating pressures of port 310, it is still possible to have all valvesopen at a predetermined pressure.

FIG. 9 is a graph illustrating the operating characteristics of twovalves, valve “1” and valve “2”, configured to open port 308 atdiffering pressures. For Valve 1, it can be seen that P_(zone 1)corresponds to flow at a higher pressure than for P_(zone 2) of Valve 2.However, P_(all) indicates flow at the same pressure for both Valves 1and 2. In each case, flow occurs of the same range of pressures.However, this can be configured, as well, for example by changing abiasing rate of biasing element 400, and/or by changing a distancebetween ports 308 and 310 for differing valves 100.

Referring now to FIGS. 7 and 8, in an alternative embodiment, a flowreservoir 500 is provided, attached to outlet 316. Reservoir 500includes a displaceable membrane 502, which is displaced by pressurefrom fluid that has passed through valve 100. When pressure at inlet 306no longer corresponds to flow through port 204, reservoir 500 cancontinue to gradually provide irrigation, for example drip irrigation,as displaceable member 502 returns to a non-displaced orientation,pushing fluid out of reservoir 500. In an embodiment, membrane 502 formsa resilient bladder, which can be, for example, rubber or plastic,although other configurations are possible, for example a spring biaseddiaphragm.

In an embodiment, reservoir 500 is connected to only one of the outletsof either the low pressure port 308 or the high pressure port 310. Forthis embodiment, manifold 314, if present, has a different configurationto enable fluid to escape from ports 308 and 310 along different flowpaths.

By using reservoir 500, pressure in a supply line can be steadilyincreased to successively and briefly charge reservoir 500 for valveswhich operate at various pressures, after which a continuous and steadyirrigation can take place as fluid is gradually released from allcharged reservoirs 500 by the biasing of membrane 502 to a non-displacedorientation. To prevent port 310 from opening, it is advantageous if themaximum pressure required to open any of valve 308 is less than apressure required to open any of valve 310, among all differentlyconfigured valves 100.

For a drip line, in an example of the foregoing, given a flow rate of 1drop being about equal to 0.05 ml; at 30 drops per min flow is about 1.5mL/min, or about 7.5 mL/5 min. Further given 50 zones and a 10 mLreservoir, cycling from valves operable at different low pressure valuescould occur at 10 second intervals, giving full control of the drip linewith 5 minute granularity. Of course, other time values and flow ratescan be configured as best meets the needs of a given crop and climate.

It should be understood that, for a given valve, more than one port 204,or more than one port 308 can be provided, enabling different lowerpressure operating values for the valve.

Thus, in accordance with the disclosure, the pressure addressable valve100 of the disclosure has the properties illustrated in the figures ofallowing fluid to be transmitted through the valve at discretepressures. This enables the valve to be addressed by selecting apressure via a regulator at the source end of a supply/drip line.Further, all valves connected to a given pipeline, or collection ofconnected pipelines, can be controlled from a single location. This canbe particularly helpful for long lines, for example a drip line of 600feet, or any length whatsoever. Valves can be organized or segmentedinto zones containing valves designed to operate at a pressure unique tothat zone.

While the embodiments shown have two zones, a lower and higher pressurezone, it should be understood that either port 308 or port 310 can beeliminated. Additionally, all valves along a given supply line canoperated at the same pressure for opening port 308. For example, valvescan be configured to open at the same low pressure value, and atdifferent pressures at a higher pressure. In this manner, a baselineirrigation can be provided for all crops, while individual zones can beprovided with water at a higher rate.

It should be understood that the shape of valve 100 and its constituentparts have been illustrated in a simple manner which bests clarifies thefunction of the parts and other aspects of the disclosure. However,these parts may have a different shape, although with the samefunctionality, to accommodate improved flow, ease of maintenance andinstallation, ease and reduced cost of manufacturing, and otherconsiderations understood within the art.

What is claimed is:
 1. A method of irrigating plants, comprising:positioning along a supply line of water, a plurality of valves, eachvalve including: a valve body including an interior surface; a fluidinlet communicating fluid into an interior of the valve body; a pistonslideable successively through first, second, third, and fourthpositions within the valve body and including: a head, a skirt formingan upper skirt portion connected to and extending from the head in adirection of the fluid inlet, the upper skirt portion forming a sealagainst the interior surface of the valve body; a piston port formed inthe upper skirt portion; a low pressure port formed through the interiorsurface of the valve body, the low pressure port sealed against theinterior of the valve body when the piston is in the first and thirdpositions, the low pressure port in fluid communication with the pistonport when the piston is in the second position; a high pressure portformed through the interior surface of the valve body, the high pressureport in fluid communication with the piston port when the piston is inthe fourth position; a biasing element positioned within the valve bodyto urge the piston head in a direction of the first position, the pistonmoveable against a biasing force of the biasing element to slidesuccessively from the first to the fourth position as the pressure atthe fluid inlet is increased configuring first and second sets of valvesdifferently, wherein configuring differently includes providing valvesin the first set relative to the second set with at least one of adifferent biasing element and a different position of the low pressureport, wherein the low pressure port of valves of the first set open at afirst pressure, and the low pressure port of valves of the second setopen at a second pressure greater than the first pressure, and the lowpressure port of the first set are closed at the second pressure;supplying water to the supply line at the first pressure wherein valvesof the first set flow water, and valves of the second set do not flowwater; and supplying water to the supply line at the second pressure,wherein valves of the second set flow water, and valves of the first setdo not flow water.
 2. The method of claim 1, wherein configuringincludes opening the valve body and replacing at least one of the pistonand the biasing element, and closing the valve body.
 3. The method ofclaim 1, wherein the biasing element is a gas or liquid under pressureadmitted to a side of the piston head opposite to a side of the pistonhead in fluid communication with the fluid inlet.
 4. The method of claim1, wherein the supply line is between 1 and 1000 feet and includesbetween 1 and 1000 valves.
 5. The method of claim 1, wherein the supplyline is a drip irrigation supply line.
 6. The method of claim 1, whereinthe piston further includes a lower skirt portion connected to andextending from the head in a direction away from the fluid inlet, thelower skirt portion forming a seal against the interior surface of thevalve body, and wherein supplying water at the first pressure includesblocking the high pressure port with the lower skirt portion.
 7. Themethod of claim 1, wherein the piston further includes a lower skirtportion connected to and extending from the head in a direction awayfrom the fluid inlet, the lower skirt portion forming a seal against theinterior surface of the valve body, and wherein supplying water at anintermediate pressure between the first pressure and the second pressureincludes blocking the low pressure port with the upper skirt portion,and blocking the high pressure port with the lower skirt portion.
 8. Themethod of claim 1, further including supplying water at a third pressurehigher than the first pressure and the second pressure, wherein the highpressure port of all of the first and second sets of valves are open. 9.The method of claim 1, wherein the valve further includes a fluidretaining chamber disposed at an outlet of at least one of the low andhigh pressure ports; a membrane dividing the chamber, the membranedisplaceable by fluid passing through the piston port and out of thevalve body and into the chamber, the membrane movable to a non-displacedconfiguration to gradually release fluid passed into the chamber whenfluid is not passing into the chamber; wherein when supplying water tothe supply line at the first pressure, water is passed into the chamberfrom the low pressure port; and wherein when supplying water to thesupply line at the second pressure, water does not pass into thechamber, and water passed into the chamber while applying the firstpressure is gradually released.
 10. A method of irrigating plants,comprising: positioning along a supply line of water, a plurality ofvalves, each valve including: a valve body including an interiorsurface; a fluid inlet communicating fluid into an interior of the valvebody; a piston slideable successively through first, second, third, andfourth positions within the valve body and including: a head, a skirtforming an upper skirt portion connected to and extending from the headin a direction of the fluid inlet, the upper skirt portion forming aseal against the interior surface of the valve body; a piston portformed in the upper skirt portion; a low pressure port formed throughthe interior surface of the valve body, the low pressure port sealedagainst the interior of the valve body when the piston is in the firstand third positions, the low pressure port in fluid communication withthe piston port when the piston is in the second position; a highpressure port formed through the interior surface of the valve body, thehigh pressure port in fluid communication with the piston port when thepiston is in the fourth position; a biasing element positioned withinthe valve body to urge the piston head in a direction of the firstposition, the piston moveable against a biasing force of the biasingelement to slide successively from the first to the fourth position asthe pressure at the fluid inlet is increased; wherein the plurality ofvalves include first and second sets of valves, and wherein valves inthe first set relative to the second set have at least one of adifferent biasing element and a different position of the low pressureport, wherein the low pressure port of valves of the first set open at afirst pressure, and the low pressure port of valves of the second setopen at a second pressure greater than the first pressure, and the lowpressure port of the first set are closed at the second pressure;addressing the first or second set of valves by supplying water to thesupply line at the first pressure wherein valves of the first set flowwater, and valves of the second set do not flow water, and supplyingwater to the supply line at the second pressure, wherein valves of thesecond set flow water, and valves of the first set do not flow water;and supplying water at a third pressure higher than the first pressureand the second pressure, wherein the high pressure port of all of thefirst and second sets of valves are open and flow water.